Fat is fat is phatt. Calories are the same. Consequences are different. Original pemmican was made with suet, the hard, sold beef kidney fat. It is packed with cholesterol. Not a good thing in the long run.
The recommendations about peanut butter are dead on. You can get it in many forms with healthier fats.
Here is an old home recipe for pemmican: 1 pound peanut butter (or substitute any nuts), 2 pounds dried fruit (prunes, raisins, currents, figs, anything) 2 cups dried cranberries or graited orange peel. Chopped jerky is optional. Run everything through a grinder, adding a handful or large spoonful at a time to promote mixing. Press into oiled/greased cookie sheets and put in warm (200 degree) oven. Put a spoon in the oven door to prop it open and leave the stuff for 5-8 hours until dry enough to be chewy, but not hard and brittle.